Can I power a tire inflator directly from battery?

Yes, you should be able to connect it to the 12V battery directly. Like your old car, I would start the car and let the HV battery and DC/DC converter supply the current to the tire inflator.

 

When the hybrid system is on, you're drawing power from the main hybrid battery. When you drain it the ICE switches on and charges. Its a pretty inefficient way to power anything, but won't hurt a thing. When you've finished what you're doing, I'd suggest letting the system run for a bit to charge itself back up. When the ICE shuts off, you're set.

 

It's popular to buy an ~1000Watt inverter and hook it to your 12volt. This can provide energy for emergencies. The Prius has to be on of course, and then the engine runs intermittently to keep the 12V charged.

 

"then the engine runs intermittently to keep the 12V charged" sure you meant HV battery

I have made this mod by the way.

For OP you must be new to prius ... because access to 12V is pretty tedious especially if you have something in the trunk. However you may find the jump port under the hood a better option especially if the pump has the clamps ...

 

Both really. The usual ~1000 watt inverter will be one that runs on 12 volts. The car keeps that battery charged using the converter under the hood to produce power at 12 volts, using power from the HV battery, which gets charged by running the engine. wjtracy might just not have thought that much detail was needed for the question at hand. In short, the hybrid system will run the engine intermittently and both batteries stay charged.

-Chap

 

I think you have some "funny" understanding how this works when you have something connected in a parallel to the 12V battery ...

NO the DC/DC converter powers the inverter along with all the stuff on the 12V bus and "floating" the 12V battery at about 13.8 V unless load is higher then certain point (I do not know exact current but A/C for sure) then it increases the voltage to somewhere 14.5-6V That is the case when inverter attached two.

The 12V battery or any additional ones MAY help buffer some load spikes but that may not actually really work in this application..

 

Nah, the same thing just happened again. I replied the first time because it seemed like a gotcha to 'correct' wjtracy for not having gone into full detail on the power flow from HV through converter to 12V bus when my guess was wjtracy just didn't think that amount of detail was needed for the OP's question. Then when I pared the explanation down to "keeps that battery charged by using the converter to produce power at 12 V" instead of delving into how the 12V bus nominal voltage isn't actually 12V when the converter's on, etc., etc., again because I wasn't sure this thread required it, I left an opening for another gotcha, which you've now delivered. What you're saying isn't wrong, we've all just made different judgments about how much of it was needed for the question at hand.

My sense is wjtracy's post could fairly be rendered as "1. if you run your 12V inverter with the car off, your 12V battery will be gradually discharged; 2. if you run the inverter with the car on, your 12V battery will remain charged, thanks to the engine intermittently running." And that's not wrong either, just (IMO) closer to the level of detail needed in a somewhat casual thread that started with a simple question. Peace.

-Chap

 

Please note that not only the sustained power need is important 1500W is probably higher than you can get safely out the prius using the 12V system.

But depending on the "tool" you want to operate, the inrush current could way exceed what inverter and the Batter(ies) can sustain. Electric motors and other stuff like purly designed switching power supply can put very high spikes at start up.

There was a long discussion and some suggested solutions on this.

I learned from experience that my old (10+year) fridge which shows 650W when the compressor is going on the grid ... would trip inverter which by specs should be able to do 2000W in surge mode.

 

I only did dry run tests with my setup. After fridge did not work I was putting small electronics and increased load with resistive only load (flood lamps). I was able to run 30-40 minutes 650W without anything heating up. Again starting the tool maybe problematic.

Also you most likely want "full sinus" inverter. For motor it may matter also less loss on the AC side. There are a few other threads here with more technical details even hard measurements. For loads like that you need "heavy" cables on the low voltage side and makes sure you fuse it as well. Blowing the inverter's fuse would be really bad.

 

I carry a 12V AGM Optima "House Battery" setup behind the center console when camping and fuse both + and - terminals for what become obvious reasons when you get into portable power supplies. I do like to avoid "inverters" like the plague since they draw 5-20W of additional power, even with nothing plugged into them. The solution is using converters, which up or down-convert 12V for your application, whether it be a 19V laptop or a 5.5v LED table lamp. I wouldn't have a problem plugging into the starting battery directly, but I'd run dedicated quick-disconnect fused leads somewhere like through the trunk tray, or behind the tail lamp bulb access so you don't have to go through removing the trunk tray to gain access. The parts to set up these things are inexpensive and easy to DIY.